Drycleaning machine with adsorber



NOV. 10, 1970 [J ETAL I 3,538,615

DRYCLEANING MACHINE WITH ADSORBER Filed March 25, 1968 Heinrich FUTIRINGJohannes Helmut SIEBER INVENTORS Attorney United States PatentDRYCLEANING MACHINE WITH ABSORBER Heinrich Fiihring, Augsburg, andJohannes Helmut Sieber, Aystetten, Germany, assignors to Bowe Bohler &Weber KG, Augsburg, Germany, a corporation of Germany Filed Mar. 25,1968, Ser. No. 715,648 Claims priority, application Austria, Mar. 23,1967, A 2,806/ 67 Int. Cl. F26!) 21/06 US. C]. 34-74 7 Claims ABSTRACTOF THE DISCLOSURE To control the moisture content in the atmosphere of adrycleaning drum during a solvent-extraction phase, air circulatedthrough the drum in a closed path is passed first through an adsorberfor the solvent, then through a condenser for the separation of excessmoisture, and finally through a heater wherein the air cooled in thecondenser is reheated before reentering the drum.

The invention relates to a method of and to apparatus for the recoveryof solvent gases from an air current issuing from the cleaning drum of adrycleaning machine, the air current being passed through a device bywhich the gases to be recovered are adsorbed and then recirculated tothe drum.

In commonly owned German patent application No. B 62,503 it has beenproposed to use for the recovery of the solvent an adsorber,particularly for low-boiling solvents, instead of the condenserotherwise used in drycleaning machines as the goods are dried. Theefficiency of the adsorber is reduced when a solvent of highconcentration is used; for this reason, a condenser is provided at theinlet of the adsorber so that the yield of solvent may be slightlyincreased. Upon regeneration of the adsorber in the opposite directionof flow, the condenser could be used simultaneously for the condensationof the mixture of water vapor and solvent. It has, however, been .foundthat the increase in yield thus obtained is very limited since theadsorption capacity of the adsorber is reduced by the increased relativehumidity of the air being cooled by the condenser. A decisivedisadvantage resulting from the use of adsorbers of this kind in asolvent-recovering circulation system consists primarily in the factthat air passing through the adsorber during the recovery phase absorbsmoisture as the solvent is adsorbed and entrains it to the drum, thismoisture having been retained in the adsorber during the precedingregeneration by means of water vapor or steam. Upon recirculation, theair absorbs further moisture whenever it passes through the adsorber.The moisture thus accumulating in the air deposits on the goods as itpasses through the drum, so that the goods absorb excessive moisturewith resultant creasing and clamminess thereof. Even when an air heateris used, the continual, ever increasing concentration of moisture in theair and the precipitation thereof on the goods cannot be preventedinasmuch as only limited air heating is permissible for the sake ofpreservation of the goods. For these reasons, the use of adsorber forthe recovery of solvents in drycleaning machines has not succeeded.

It is the principal object of the invention to eliminate by simple meansthe aforementioned disadvantages resulting from the use of an adsorberfor the recovery of the solvent in air-circulation systems ofdrycleaning machines, and to prevent an undesired creasing of the goods.It is a further object of the invention to ensure uniform conditioningof the goods to be treated, so that a predetermined, desired state ofmoisture may be produced in the finished goods. Here and in thefollowing the term moisture" applies to the water content.

In accordance with the invention, all of the moisture, except for adesired residual quantity, is withdrawn from the air stream by coolingas it circulates through the adsorber, after it has issued therefrom,and before its readmission to the cleaning drum. It is thus ensured thataqueous moisture entrained from the adsorber by the air current islargely eliminated therefrom before it can spoil the goods, only apredetermined quantity of moisture which may be controlled by the degreeof cooling being retained in the air admitted to the drum.

In accordance with the invention, the air is advantageously reheated toa desired temperature immediately after the cooling process in order toensure that the process of evaporation in the drum should not be tooslow. In the recovery of the solvent by means of a condenser it is knownto heat the air after it has left the condenser and before it isadmitted to the drum. We have found, however, that, in connection withthe cooling of the air issuing from the adsorber, a subsequent heatingaffords particular advantages since a predetermined, desiredconcentration of water vapor in the air present in the drum, i.e., acertain relative humidity may be produced simply by adjusting thecooling and the heating to corresponding values. The cooling and heatingof the air are used for the elimination of "water and for controllingthe air moisture rather than for the recovery of the solvent, as hasbeen the case in conventional plants.

The use of adsorbers in the air-circulation system of drycleaningmachines affords particular advantages when a low-boiling solvent, forexample a fiuorinated chlorinated hydrocarbon, is used since then acondensation plant of high cooling power would have to be provided, orelse a correspondingly high loss of solvent would have to be accepted.

In accordance with the invention, apparatus for carrying out theaforedescribed method comprises a drycleaning machine provided with acleaning drum mounted, for example, in a housing and provided withperipheral openings for the passage of air and solvent, these openingsbeing connected by conduits to the inlet and to the outlet of anadsorber to form a recirculation system between the drum and theadsorber. The chamber of any other type of drying plant, in which thegoods to be dried are to be protected against being moistened by water,may be substituted for the cleaning drum of a drycleaning machine.

In apparatus according to the invention, in which the movement of theair may be produced by a fan or the like, an indirectly cooled condenseris provided in the zone of the recirculation system between the outletof the adsorber, i.e., the location where the recirculated air .issuesfrom the adsorber, and the inlet of the drum. The

air issuing from the adsorber is cooled by the condenser until itcontains only a desired quantity of residual moisture.

In one advantageous construction of apparatus according to theinvention, the condenser is provided with adjustable cooling means, asby making the supply of coolant adjustable. A desired rate of cooling,corresponding to a predetermined moisture content in the air admitted tothe drum, may thus be selected by simple means. Thus, for example, thecooling of the condenser may be controlled by means of a suitablesensing device in dependence upon the temperature of the coolant issuingfrom the condenser. It is thus ensured that the air issuing from thecondenser and readmitted to the drum contains a quantity of moisture notexceeding a predetermined maximum.

In one embodiment of the invention, an air heater of conventionalconstruction is provided downstream of the condenser and upstream of theinlet of the drum, in order to establish a predetermined relativehumidity in the drum atmosphere. In accordance with the invention, theoutput of the heater may be controlled so that various degrees ofrelative humidity, or an air moisture content not exceeding apredetermined maximum, may be produced thereby in the drum withcorrespondingly adjusted precooling to selected temperatures. The use ofan air heater in connection with a cooling of the condenser indrycleaning machines is known; this technique, however, has heretoforebeen used only for the purpose of recovering the solvent and not forcontrolling and proportioning the moisture content in the drumatmosphere in connection with an adsorber provided in a closedaircirculation system.

A further feature of our invention is the provision of means forregulating the thermal output of the heater, as by controlling the steamsupplied thereto or the heating voltage or heating current with the aidof, for example, a temperature sensing element, according to thetemperature of the air issuing from the heater. In accordance withanother feature of the invention, the cooling of the condenser, forexample the supply of cooling water, may also be controlled, e.g., by ahydrometer, in dependence upon the relative humidity of the air issuingfrom the heater. The invention thus also enables automatic adjustmentand maintenance of the desired air moisture in the drum of a drycleaningmachine.

The invention is diagrammatically illustrated by way of example in thesole figure of the accompanying drawing in which the cleaning drum, orthe housing enclosing it, is denoted by the reference numeral 1. Thedrum is loaded and unloaded through a hatch 2. A conduit 3, which maycontain a lint filter 4, is connected to the drum 1 or to the housingenclosing it. In the illustrated construction, the conduit 3 extends toa blower 6 driven by a motor 5.

The blower 6 draws the solvent-containing air present in the drum 1through the conduit 3 and then passes it under pressure into anadjoining adsorber 7 filled, for example, with activated carbon. Theadsorber 7 withdraws solvent from the air flowing through it. Asillustrated in the drawing, a filter 8 retaining particles of carbon andthe like, entrained by the air current from the adsorber 7, may beprovided at the outlet thereof. The filter 8 is followed by a condenser9 for cooling the air issuing from the adsorber 7. A conduit 10 extendsfrom the condenser Q back to the drum 1. The condensate recovered in thecondenser 9 and collected in a drain trough 11 may be fed through aconduit 12 to a collecting device 13 advantageously constructed as awater separator. The direction of flow of the circulating air isindicated by arrows. Other valves, flaps, terminals, and the like, whichhave no direct connection with the invention, have been omitted from thedrawing for the sake of clarity.

The water in vapor form entrained from the adsorber and originating fromthe preceding regeneration process is withdrawn from the air by thecondenser 9 by corresponding adjustment of the cooling. The residualquantity of moisture entrained by the air issuing from the condenser 9varies in accordance with the adjusted cooling power of the condenser 9and can thus be controlled as desired.

A device for controlling the quantity supplied may be provided, forexample in the supply line 14 for the cooling water, so that the coolingrate of the condenser 9 may be adjusted to a desired value. The controldevice 15 may be operated preferably by a device 16 for measuring thetemperature of the coolant issuing from the condenser. The adjustment ofthe control device 15 by the measuring device 16 is diagrammaticallyindicated by a broken line 17.

In the illustrated embodiment of our invention, a heater 18 ofconventional construction is provided upstream of the inlet of the drum1 in the branch conduit 10- between the condenser 9 and the drum 1, sothat a desired relative humidity may be established in the drumatmosphere, and particularly so that the quantity of water absorbed orgiven off by the goods from or to the air may be adjusted; apredetermined desired conditioning of the goods may thus be obtained.Thus, with a given rate of cooling in the condenser 9, a predeterminedrelative humidity may be produced by adjusting the heater 18; similarly,with a given permanent adjustment of the heater 18, this may be achievedby corresponding variation of the cooling action of the condenser 9. Adevice 19 for adjusting the heater 18 by controlling the supply ofenergy thereto is provided in the energy-supply line 19 (the heater may.be operated either with steam or With electrical energy). In onespecific construction, the adjustment of the control device 19 iscarrier out by a device 20 which measures the temperature of the air atthe outlet of the heater. In the drawing, the control of the adjustingdevice 19 by the measuring device 20 is diagrammatically indicated by abroken line 21.

The supply of coolant to the condenser 9 may also be controlled directlyby operating the control device 15, even when the heater 18 has apermanently adjusted output, by having the measuring device 20 sense therelative humidity of the air issuing from the heater instead ofmeasuring the temperature thereof. This further means of control isindicated diagrammatically in the drawing by a dash-and-dot line 22.

In accordance with the invention, an absorber which has been foundparticularly advantageous for the recovery of low-boiling solvents maybe used for the recovery of the solvent by recirculation, the hithertoexisting danger of excessive moisture passing from the adsorber to thegoods being no longer present. Over and beyond this, the inventionafifords the advantage that an excessive drying of the goods in the drumis prevented and the realtive humidity of the drum atmosphere may becontrolled by simple means even at realtively low drying temperatures,so that the goods may be conditioned as desired. The goods are subjectedto substantially less strain than in conventional cleaning machines,since the heater may be operated at a low temperature.

The construction and disposition of an adsorber in drycleaning machines,in which the condenser is provided downstream of the adsorber as viewedin the direction of flow of the circulating air, may be realized invarious ways, so that the invention is not limited to the illustratedconstruction. It will be readily understood that the invention may alsobe applied to systems, operating exclusively as drying plants, in whichsimilar problems exist.

We claim:

1. A method of controlling the moisture content of the atmosphere of adrycleaning vessel during extraction of residual solvent from goods insaid vessel, comprising the steps of recirculating an air stream throughsaid vessel in a closed path including an adsorber for removingentrained solvent therefrom, said adsorber having been previouslyregenerated by flushing with an aqueous medium leaving a residue ofmoisture therein, separating excess moisture from said air stream bycooling same at a first location downstream of said adsorber andreheating said air stream at a second location between said firstlocation and said vessel.

2. A method as defined in claim 1 wherein the cooling rate of said airstream at said first location is controlled in dependence upon themoisture content of the air stream between said second location and itspoint of reentry into said vessel.

3. In a drycleaning plant including a vessel for the treatment of goodswith a solvent, the combination therewith of conduit means forming aclosed path for the pas sage of an air stream through said vessel duringa solvent-extraction phase, blower means in said path for recirculatingsaid air stream, adsorber means in said path for removing entrainedsolvent from said air stream after passage thereof through said vessel,said adsorber means being regeneratable by an aqueous medium leaving aresidue of moisture therein, condenser means in said path downstream ofsaid adsorber means for separating excess moisture from said air streamby cooling same, and heater means in said path between said condensermeans and said vessel for reheating said air stream before its reentryinto said vessel.

4. The combination defined in claim 3, further comprising filter meansin said path between said absorber means and said condenser means forremoving entrained particles of adsorber material from said air stream.

5. The combination defined in claim 4, further comprising additionalfilter means in said path ahead of said adsorber means, said blowermeans being disposed between said additional filter means and saidadsorber means.

6. The combination defined in claim 3, further comprising control meansfor varying the cooling eifect of said condenser means.

7. The combination defined in claim 6, further comprisingmoisture-sensing means in said path between said heater means and saidvessel, said control means being responsive to said moisture-sensingmeans for maintaining a predetermined humiditydevel in said vessel.

References Cited UNITED STATES PATENTS FREDERICK L. MATTERN, JR.,Primary Examiner 20 H. B. RAMEY, Assistant Examiner US. Cl. X.R.

